Field of the Invention
The present invention relates to a non-contact electric power transmission system and a charging station.
Description of the Background Art
Japanese Patent Laying-Open No. 2013-135572 discloses a non-contact charging system in which electric power is transmitted from a vehicle to a charging station in a non-contact manner. In the non-contact charging system, positioning between an electric power transmission portion of the charging station and an electric power reception portion of the vehicle is carried out in order to enhance efficiency in electric power transmission and reception.
In spite of positioning as disclosed in the publication above, however, it is also possible that charging is not carried out immediately after positioning. For example, in spite of completion of positioning at the time of parking, a weight may vary when a passenger gets off a vehicle or a vehicle is unloaded subsequently, and in particular, a height of the vehicle may vary and efficiency in electric power transmission and reception may consequently be varied. When charging is started after lapse of some time since completion of positioning owing to timer setting, a position may have been displaced due to application of external force during parking.
Displacement of a position of a vehicle results in position displacement between an electric power transmission coil and an electric power reception coil at the time of start of full-scale charging. When electric power is transmitted similarly to a case of good positioning with the position having been displaced, electric power transmission efficiency may lower or an electric power transmission device may be damaged by reflected electric power.
A charging station may also be configured such that a single control unit controls a plurality of electric power transmission coils. In such a configuration, an electric power transmission coil at a position where a vehicle is stopped should be determined and then full-scale charging should be carried out. In such a case, processing for determining an electric power transmission coil and positioning processing are required, however, the problem of position displacement after completion of positioning above should similarly be overcome.